1. Field of the Invention
The present invention relates to a projector, and more particularly, to a projector including a shiftable projection lens unit.
2. Discussion of the Related Art
The recent tendency of display devices is to provide a large screen size as well as lightness and thinness.
Of such display devices, projectors have been greatly highlighted because they can realize a large screen of 100 inches or more.
Such a projector is a display device which projects an image produced by a micro device such as a liquid crystal display (LCD) panel, a liquid crystal on silicon (LCOS) panel, or a digital micromirror device (DMD) panel, onto a screen, thereby displaying the image.
Generally, such a projector is classified into a single panel type, a double panel type, or a triple panel type in accordance with the number of micro devices used in the projector.
In a single panel type projector, white light is separated into color light components in a time-division manner, and the separated color light components are illuminated to a single micro device. In a two-panel type projector, white light is separated into color light components in a space-division and time-division manner, and the color light components are illuminated to two micro devices. In a three-panel type projector, white light is separated into color light components in a space-division manner, and the color light components are illuminated to three micro devices.
FIG. 1 is a schematic view illustrating an arrangement of a general single panel type projector. FIG. 2 is a perspective view illustrating an appearance of the projector shown in FIG. 1.
As shown in FIG. 1, the single panel type projector includes a light source 2, a color wheel 3, a light tunnel 4, illumination lenses 5 and 6, a micro device 7, a prism 8, and a projection lens unit 1.
In the illustrated single panel type projector, light emitted from the light source 2 is separated into red, green, and blue light beams. The separated light beams are modulated to have uniform brightness while passing through the light tunnel 4. The light beams are then incident on the micro device 7 after passing through the illumination lenses 5 and 6 and the prism 8.
The incident light carries an image signal while passing through the micro device 7, and is then projected onto a screen via the prism 8 and projection lens unit 1.
In the conventional projector having the above-mentioned arrangement, the projection lens unit 1 and micro device 7, which serve to externally emit light in an enlarged state, are arranged in parallel, whereas the lenses 4, 5, and 6 and color drum 3, which transfer light from the light source 2, are arranged perpendicularly to the projection lens unit 1.
As shown in FIG. 2, the projection lens unit 1 includes a plurality of lenses which are,-arranged in parallel such that the direction of light emitted from the projection lens unit 1 is identical to the direction of light incident on the projection lens unit 1.
Due to such an arrangement of the projection lens unit 1, the optical elements in the optical system of the conventional projector are arranged in a U shape. As a result, the conventional projector has an increased thickness.
As a result, the conventional projector has a problem in that there is a limitation to the installation space of the projector because an increased space must be provided in rear of the front side of the projector where the projection lens unit is arranged.